def resolve():
    num = int(input())
    if num >= 30:
        print("Yes")
    else:
        print("No")
        
resolve() def resolve():
    num = int(input())
    if num >= 30:
        print("Yes")
    else:
        print("No")
         resolve num = int(input()) num int(input()) int input() input if num >= 30:
        print("Yes")
    else:
        print("No")
         num >= 30 num 30 print("Yes") print "Yes" print("No") print "No" resolve() resolve def resolve():
    num = int(input())
    if num >= 30:
        print("Yes")
    else:
        print("No")
         def resolve():
    num = int(input())
    if num >= 30:
        print("Yes")
    else:
        print("No")
         resolve
def resolve():
    num = int(input())
    if num >= 30:
        print("Yes")
    else:
        print("No")
        
resolve()